Paper and Board Manufacture and Properties …

1 Paper and Board Paper and Board Manufacture and Properties Manufacture and Properties WorkshopWorkshopCharles P. KlassCharles P. KlassKlass Associates Associates Beach, FLRedington Beach, FLSummary of WorkshopSummary of WorkshopzzOverview and terminology of Paper and Overview and terminology of Paper and Board grades that are extrusion coatedboard grades that are extrusion coatedzzProperties of Paper and Board used for Properties of Paper and Board used for extrusion coatingextrusion coatingzzPaper and Board manufacturing variables Paper and Board manufacturing variables that impact extrusion coatingthat impact extrusion coatingzzTrends and developmentsTrends and developmentszzGeneral group discussionGeneral group discussionExtrusion Coated GradesExtrusion Coated GradeszzExtrusion coating is applied to a wide Extrusion coating is applied to a wide variety of Paper and Board grades variety of Paper and Board grades depending

2 On the Properties soughtdepending on the Properties soughtzzExtrusion coating/lamination can be used Extrusion coating/lamination can be used to bond foil to Paper or paperboard for to bond foil to Paper or paperboard for enhanced barrier propertiesenhanced barrier propertiesExtrusion Coated GradesExtrusion Coated GradesSubstrateSubstrateProperty SoughtProperty SoughtEnd UsesEnd UsesBag and wrapping Bag and wrapping paperpaperMVTR, OGR, MVTR, OGR, liquid resistanceliquid resistanceQSR, bakery, QSR, bakery, carrycarry--out, multiwall out, multiwall sackssacksBleached boardBleached boardLiquid resistanceLiquid resistanceCups, milk cartonsCups, milk cartonsLinerboardLinerboardMVTR, OGR, MVTR, OGR, liquid resistance, liquid resistance, releasereleaseFrozen food & Frozen food & other packagingother packagingVariability of PaperVariability of PaperzzPaper is not a homogeneous is not a homogeneous in the machine direction (MD), crossVaries in the machine direction (MD), cross--direction (CD), Zdirection (CD), Z--direction, and over , and over is also reactive to changes in its environment.

3 It is also reactive to changes in its environment. Shrinks and expands and usually not and expands and usually not structure depends on the process that Its structure depends on the process that produced it and even the location across the produced it and even the location across the width of the Paper of the Paper of PaperVariability of PaperComponents of WoodComponents of WoodzzCellulose Cellulose 45%45%zzLignin Lignin 25%25%zzHemicelluloses Hemicelluloses 25%25%zzExtractives Extractives 5%5%Wood TissueWood TissueInner BarkInner BarkCambiumCambiumCellulose (CCellulose (C66HH1010OO55))nnFiber StructureFiber StructurePAPRICANF iber StructureFiber StructureLumenLumenS3 LayerS3 LayerS2 LayerS2 LayerS1 LayerS1 LayerPrimary wallPrimary wallLigninLigninMiddle lamellaMiddle lamellaFiber StructureFiber StructurezzLike a drinking strawLike a drinking strawzz1/321/32 ( ) to ( ) to 1/41/4 (6mm) long(6mm)

4 LongzzLength to width ratio Length to width ratio of 50 to 140of 50 to 140 Fiber StructureFiber StructureFiber StructureFiber StructurePine sheetPine sheetEucalyptus sheetEucalyptus sheetFiber StructureFiber StructurezzSoftwoods for strength and runnabilitySoftwoods for strength and runnabilityzzHardwoods for uniformity, smoothness, Hardwoods for uniformity, smoothness, formation, and printabilityformation, and printabilityzzInherent strength requirement of the Inherent strength requirement of the converting process dictates the amount of converting process dictates the amount of softwood that is included in the furnishsoftwood that is included in the furnishPulping and BleachingPulping and Bleachingzz65% of the pulp produced in the world is 65% of the pulp produced in the world is made by the kraft by the kraft pulping removes most of the Chemical pulping removes most of the lignin and hemicelluloses and all of the lignin and hemicelluloses and all of the , chemical pulping results in dark However.

5 Chemical pulping results in dark brown pulp that must be pulp that must be all extrusion coated Paper and Nearly all extrusion coated Paper and Board is made from kraft pulp. Board is made from kraft pulp. Paper StructurePaper StructurezzCellulose molecule is aligned more or less Cellulose molecule is aligned more or less parallel to the long axis of the to the long axis of the are are expand and shrink based on the water Fibers expand and shrink based on the water content in the fiber in the fiber can swell up to 25% in width but only Fibers can swell up to 25% in width but only slightly in in results in fiber swelling, greater fiber Hydrolysis results in fiber swelling, greater fiber flexibility, and fiber , and fiber StructurePaper StructurePagePaper StructurePaper StructureSide viewTop viewMore fiber collapseLess fiber collapsePaper StructurePaper StructureFiber collapse depends on:Fiber collapse depends on.

6 ZzThickness of the cell wallsThickness of the cell wallszzRatio between fiber wall thickness and Ratio between fiber wall thickness and fiber widthfiber widthzzAmount of lignin left in the fiber wallAmount of lignin left in the fiber wallzzAmount of mechanical actionAmount of mechanical actionzzPressure on the Paper machinePressure on the Paper machinePaper StructurePaper StructurePaper StructurePaper StructurePaper StructurePaper StructureFiber orientation means that Paper is stronger in the machine direction than in the cross machine StructurePaper StructurePaper StructurePaper StructurezzMore fiber alignment in More fiber alignment in the MD is called the MD is called modulus relates Sonic modulus relates to tensile stiffness to tensile stiffness index (TSI).

7 Index (TSI).zzTSI relates to fiber TSI relates to fiber StructurePaper StructurezzTSO is the angle of max TSO is the angle of max not be in the exact Might not be in the exact across the across the asymmetrical Called asymmetrical StructurePaper StructurezzFibers swell in width, Fibers swell in width, but not in not in changes Humidity changes affect the CD more affect the CD more than the the problem if top Same problem if top and bottom of the sheet and bottom of the sheet is of PapermakingSummary of PapermakingzzPaper is a record of all the processes that have Paper is a record of all the processes that have occurred in its production, and those processes occurred in its production, and those processes are inherently inherently physical Properties of Paper are based on The physical Properties of Paper are based on the structure of the cellulose molecule, the type the structure of the cellulose molecule, the type of fiber, and how that fiber was separated from of fiber, and how that fiber was separated from the other components of the other components of the way the fibers are reassembled strongly The way the fibers are reassembled strongly affects how the Paper reacts to further affects how the Paper reacts to further converting operations and other changes in its converting operations and other changes in its Stock QuestionsBase Stock QuestionszzEnd use requirements?

8 End use requirements?zzIs the base stock made to be Is the base stock made to be coated?coated?zzAre you making or buying?Are you making or buying?zzCan you specify or must you Can you specify or must you adapt?adapt?Roll Quality for OffRoll Quality for Off--Machine Machine CoatingCoatingzzClean slit edgesClean slit edgeszzNo edge cracksNo edge crackszzUniform tension Uniform tension --no wrinklesno wrinkleszzNo holesNo holeszzSplicesSpliceszzMinimal numberMinimal numberzzProperly made and markedProperly made and markedSpecifying Base StockSpecifying Base StockPhysical PropertiesPhysical PropertieszzBasis weightBasis weightzzMoistureMoisturezzCaliperCaliper zzStrengthStrengthzzTensileTensilezzTear TearzzInternal bondInternal bondzzFolding enduranceFolding endurancezzPorosityPorosityzzSmoothness/ roughnessSmoothness/roughnesszzCoefficie nt of Friction (COF)Coefficient of Friction (COF)

9 ZzScoring and bending propertiesScoring and bending propertiesSpecifying Base StockSpecifying Base StockOptical PropertiesOptical PropertieszzBrightnessBrightnesszzShadeS hadezzGlossGlossPaper and Board TestingPaper and Board TestingStrength PropertiesStrength PropertieszzFolding EnduranceFolding EndurancezzScott Bond (Internal Bond)Scott Bond (Internal Bond)zzStiffnessStiffnesszzBending Resistance of Paper Bending Resistance of Paper Gurley Gurley MethodMethodzzStiffness of Paperboard Stiffness of Paperboard Taber MethodTaber MethodzzTearing ResistanceTearing ResistancezzTensile StrengthTensile StrengthFolding EnduranceFolding EndurancezzFolding endurance is tested using the MIT testerFolding endurance is tested using the MIT testerzzA strip of Paper is mounted under tension in the A strip of Paper is mounted under tension in the testertesterzzThe tester rotates back and forth through 270 The tester rotates back and forth through 270 zzThe number of double folds is reported The number of double folds is reported either as either as raw data or lograw data or log1010zzISO 5626 and TAPPI T

10 511 are the folding endurance ISO 5626 and TAPPI T 511 are the folding endurance test methodstest methodsScott Internal BondScott Internal BondzzMeasures the internal Measures the internal bond strengthbond strengthzzVery critical for offset Very critical for offset printing printing especially especially sheet fed offset with sheet fed offset with high tack inkshigh tack inkszzResistance to fiber Resistance to fiber pickingpickingzzTAPPI T 569 TAPPI T 569 Gurley Stiffness for PaperGurley Stiffness for PaperzzBending resistance is Bending resistance is important for sheet fed important for sheet fed offsetoffsetzzSample is clamped and Sample is clamped and used to deflect a used to deflect a pendulum with weightpendulum with weightzzData is reported in Data is reported in Gurley stiffness unitGurley stiffness unitzzTAPPI T 543 TAPPI T 543 Taber Stiffness for Taber Stiffness for PaperboardPaperboardzzDetermines the bending moment Determines the bending moment in gram centimeters required to in gram centimeters required to deflect the free end of a 38deflect the free end of a 38--mm mm wide sample 15wide sample 15 from its from its centerline with a load applied 50 centerline with a load applied 50 mm away from the clampmm away from the clampzzTAPPI T 489 TAPPI T 489 Elmendorf Tear TesterElmendorf Tear TesterzzPaper sample is torn Paper sample is torn through a fixed distance through a fixed distance by means of a pendulumby means of a pendulumzzThe work done in tearing The